Dropdown Menu with Cool Effect

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Cool Dropdown Menu</title>
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Raleway:[email protected]&display=swap" rel="stylesheet"> 
    <style>
        * {
            margin: 0;
            padding: 0;
            font-family: 'Raleway', sans-serif;
        }

        body {
            background-color: #292929;
        }

        section {
            display: flex;
            width: 100%;
            height: 100vh;
            justify-content: center;
            align-items: center;
            flex-flow: column;
        }

        nav {
            width: 200px;
        }

        button {
            width: 100%;
            font-size: 18px;
            padding: 10px 0;
            border: none;
            border-radius: 3px;
            cursor: pointer;
        }

        ul {
            list-style: none;
            margin-top: 10px;
        }

        ul li {
            margin: 5px 0;
            border-radius: 3px;
            opacity: 0;
            transition: 0.5s all cubic-bezier(0.175, 0.885, 0.32, 1.275);
            transition-delay: calc(0.1s * var(--i));
        }

        ul li:nth-child(odd) {
            background-color: #2e86de;
            transform: rotateZ(50deg);
            transform-origin: left center;
        }

        ul li:nth-child(even) {
            background-color: #54a0ff;
            transform: rotateZ(-50deg);
            transform-origin: right center;
        }

        ul.active li {
            opacity: 1;
            transform: rotateZ(0deg);
        }

        ul li a {
            color: #fff;
            text-decoration: none;
            font-size: 18px;
            padding: 8px 10px;
            display: block;
        }
    </style>
    <script>
        function toggleMenu() {
            let menu = document.getElementById('menu');
            menu.classList.toggle('active');
        }
    </script>
</head>
<body>
    <section>
       <nav>
            <button onclick="toggleMenu()">Web Dev Items</button>
            <ul id="menu">
                <li style="--i:1"><a href="">HTML/CSS</a></li>
                <li style="--i:2"><a href="">JavaScript</a></li>
                <li style="--i:3"><a href="">PHP</a></li>
                <li style="--i:4"><a href="">Python</a></li>
                <li style="--i:5"><a href="">NodeJs</a></li>
            </ul>
       </nav>
    </section>
</body>
</html>

Result Screenshot(s)

Dropdown Menu with Cool EffectWorking Sample0